During most cardiopulmonary bypass surgery procedures, the patient is administered heparin for anticoagulation. Subsequent to the cardiopulmonary bypass surgery, it becomes necessary to reverse the anticoagulation state. Typically, protamine sulfate is administered to reverse the heparin-induced anticoagulation. Heretofore, there has been no viable alternative to the administration of protamine for heparin reversal short of allowing the patient to metabolize and eliminate the heparin.
Administering protamine has raised concerns in the medical community because several types of adverse reactions to protamine in the presence of heparin have occurred. Adverse reactions that have been documented include systemic and pulmonary edema, fatal anaphylaxis, thrombocytopenia and altered platelet function, complement activation, and postoperative heparin rebound. It has been estimated that anywhere from 3,500 to over 70,000 open heart patients each year are affected by adverse reactions upon administration of protamine in the United States alone. Despite efforts to circumvent potential problems, patients that become hypertensive because of the administration of protamine are still being encountered. As a consequence, there is some anticipation that more fragile, aging and diabetic patients are at greater risk of adverse effects.
Research seems to indicate that the formation of the insoluble protamine-heparin complex is key to initiating many of the adverse hemodynamic responses. Such responses are not seen in the administration of protamine alone prior to any heparinization. Consequently, there is some pressure to solve the heparin removal problem by avoiding the use of protamine.
Although there are developments that may reduce the need for the administration of heparin as an anticoagulant for extracorporeal procedures, the need for achieving anticoagulation in the surgical field continues. Hence, the need to counteract the anticoagulant effect of heparin will remain.
An additional concern is that any device or method used to reverse the heparin must not compromise the cardiopulmonary bypass circuit or the patient. Avoidance of additional incisions or operative procedures is paramount for the well-being of the patient and would minimize the possibility of complications.
Hence, it would be a significant advance in the art if reversal of heparin could be accomplished using a cannula that can be inserted rapidly into the same incision or even the same venous return cannula used for the cardiopulmonary bypass circuit during the surgery, and can be removed rapidly to permit reintroduction of the cardiopulmonary bypass circuit used during the surgery if the surgeon believes such is necessary. It would be a further advance if a system utilizing the cannula and a plasma separator could be used as a high flow extracorporeal blood circulation circuit to remove selectively certain non-cellular blood components.